[23p-E205-1~18] 10.4 Spintronics in semiconductor, topological material, superconductor, and multiferroics

[23p-E205-6] Present status of preparing a room-temperature circular polarization spin-LED

〇Hiro Munekata¹, Shigeru Kaku², Nozomi Nishizawa¹ (1.Tokyo Tech IIR, 2.Tokyo Tech Sch. Sci.)

Keywords:spin light-emitting-diodes, circular polarization electroluminescence, spin tunnel oxide layer

Since the report of nearly pure circular polarization electroluminescence (CP-EL) at room temperature from the edge-emitting, GaAs/AlGaAs-based spin-LEDs, we have been working on this subject aiming at development of methods for preparation of Al_xO_y tunnel layers that are robust against both electrical stress of J>100 A/cm² and wet-lithography process for stripe-electrodes formation: the former spin-LEDs were usually short circuiting at the stage when CP-EL took place, and moreover, the former naturally oxidized Al epilayers tended to dissolve into an alkaline-based developer during the photolithograph process for ferromagnetic stripe electrodes.
Here we report results of four new approaches: (1a) oxidation of atomically flat AlAs epilayers instead of Al epilayers and (1b) subsequent high-temperature post oxidation, (2) direct sputter-deposition of non-magnetic-metal/ferromagnetic-metal stripe electrode pads on thus prepared Al_xO_y tunnel layers through mechanical masks, and (3) pulse-current operation of spin-LEDs with duration 10 micro-sec.